Summer 2005
Ten days (5/31 through 6/9) were spent at Upper and Lower Murray Lakes on Ellesmere Island. Initial activity focused on surveying the bathymetry of both Upper and Lower Murray lakes in order to locate promising sites for core recovery. In Upper Murray Lake, the deepest depth (83 m) was measured in the northwest portion of the lake. The deepest depth recorded in Lower Murray Lake was 46m. Near anoxic conditions (0.1 mg L^-1), which are favorable for the preservation of laminated sediments, were found within 1m of the bottom in Upper Murray Lake (in Lower Murray Lake near-bottom dissolved oxygen was 3.3 mg L^-1).

Coring took place in the deepest basins of both lakes. Using a Uwitec percussion coring system two adjacent, ~8.5m long, overlapping cores were recovered from Upper Murray Lake. In addition, multiple surface cores were collected using a hand held gravity corer and an Ekman dredge. In Lower Murray Lake the Uwitec corer was used to recover two overlapping cores extending ~14.5m, and a number of surface cores were collected with the gravity corer and Ekman dredge. In total, over 40m of sediment was recovered from the Murray Lakes.

In order to gain a better understanding of the annual cycle of sediment input to the lakes, sediment traps were deployed in both Upper and Lower Murray Lakes. Two sediment traps were moored near the coring locations in each lake, with one trap just above the bottom and the second suspended 10m below the lake surface. Each trap measures sediment accumulation at 6 hour intervals and records water temperature at 1 hour intervals. Additionally, two air temperature loggers were deployed in order to examine the relationship between changes in air temperature and sediment accumulation. One temperature sensor was installed at the elevation of the lakes, while the second temperature sensor was installed 500m above the lake surface, on the slope leading up to the Hazen Plateau.

May 2006
We visited the Taconite Inlet lakes (C1, C2, and C3) for a week in late May. During this period we used a submersible vibracorer to collect long cores from each of the three lakes. The length of the record in the different lakes varies considerably. In C2, the lacustrine sediment package only extends ~1m before reaching marine sediments and then glacial till. On the other hand we collected over 5m of sediment from C3 without reaching the bottom of the lacustrine record. In addition, we measured water column properties (conductivity, temperature, depth, ph, turbidity, dissolved oxygen) in each of the lakes and recovered short surface cores containing intact sediment water interfaces – these short cores are essential for understanding recent changes are used to calibrate long term records.

August 2006
In mid August we returned to Ellesmere Island to carry out additional field work on Upper and Lower Murray Lakes and South Sawtooth Lake. The goal was use an inflatable boat to access the lakes during ice-free conditions and use a chirp sub-bottom profiler to acoustically map sedimentary features within the lake basins. The Murray Lakes remained about 70% covered by ice and so we were unable to acquire full coverage of the lake, nonetheless we observed many interesting features in the sonar images. On the other hand, Sawtooth Lake was almost completely ice-free and as a result we were able to obtain excellent sonar coverage, and mapped the entire lake.